Synonyms: Exstrophia splanchnica, exstrophy-epispadias complex.

Definition: Complex anomaly of the urogenital tract and intestinal tract resulting in exstrophy of both bowel and bladder; the most severe form of anomalies in the exstrophy-epispadias complex.

Prevalence: 0.25-0.5:10,000^1,2.

Etiology: Unknown, sporadic incidence.

Pathogenesis: Failure of two concomitant mesodermal migrations: first, the urorectal septum fails to develop and divide the urogenital sinus from the rectum; second, the mesodermal proliferation forming the infraumbilical abdominal wall and genital tubercle fails to develop. The failure of these two events to occur results in exstrophy of both bladder and intestine.

Associated anomalies: Commonly associated with other anomalies including cardiovascular, central nervous system, omphalocele (70-90%), vertebral anomalies (46%), upper urinary tract (42%), malrotation (30%), lower extremity anomalies (30%), double appendix (30%), absent appendix (21%), short small bowel (19%), small bowel atresia (5%), abdominal musculature deficiency (1%)³.

Resulting anomalies: Anomalous exposure of a poorly developed hindgut through an abdominal wall defect, resulting in two hemibladders lateral to the hindgut. No anus or anal canal is formed. In males, the two halves of the phallus are separated. In females, a bicornuate uterus and duplicated vagina are common. The vagina enters the bladder. The ureters insert caudally on the bladder. There is wide separation at the symphysis pubis.

Differential diagnosis: Bladder exstrophy, gastroschisis, isolated omphalocele.

Prognosis: Prior to 1960, cloacal exstrophy was considered uniformly fatal. Since then the mortality rate has decreased to less than 50%². Urinary continence for 3-4 hours has been achieved in 43% of patients in one series².

Risk of recurrence: Unknown for subsequent pregnancy and patient"s offspring, as reproduction in these patients has not been reported.

Management: When the diagnosis is made before viability, the option of termination of pregnancy could be offered. Postnatal management: A staged surgical approach is used: repair of the omphalocele and construction of an ileostomy or colostomy; at 9-12 months, either primary repair of the bladder or urinary diversion by ileal or colonic conduit is performed. There is some preliminary experience with early primary closure/reconstruction in the first few days of life. In genetic male patients with inadequate phallic development, female sex is assigned at birth. Otherwise, penile lengthening is performed at 1-5 years. Clitoroplasty, mons­plasty or vaginal septum resection may be required in females.

MESH Cloaca;-abnormalities BDE 3193 ICD9 751.5 CDC 751.550

Address correspondence to Roy Erb, MD, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 21^st and Garland Ave, Nashville, TN 37232-5316. Ph: 615-343-0595; Fax: 615-343-4890. §Dept of Ob-Gyn, University of Illinois, ¶Pediatric Urology, Vanderbilt University

Introduction

Cloacal exstrophy is a rare congenital anomaly that is the most severe form of the exstrophy-epispadias complex. Less than 12 cases have been diagnosed prenatally. In this report we present two cases of cloacal exstrophy and discuss the embryology, ultrasonographic appearance, management, and prognosis.

Case #1

A 19-year-old G₃P₂ patient was transferred for further evaluation of absent bladder suggested by prenatal sonogram at approximately 21 weeks EGA. A repeat ultrasound at our institution at 23 weeks EGA confirmed the prior findings of non-visualization of the urinary bladder, a two-vessel umbilical cord, normal kidneys and amniotic fluid volume. In addition, abnormal external genitalias and a soft tissue mass on the infraumbilical abdominal wall were noted (fig. 1-3).

Fig. 1: Coronal view of the pelvis, demonstrating the absence of bladder.

Fig. 2: Sagittal view that demonstrates a soft-tissue mass of the lower abdomen.

Fig. 3: View of the abnormal genitalias.

A percutaneous umbilical blood sampling was performed at 25-26 weeks of gestation for rapid fetal karyotyping, revealing a 46XX normal female. There was no family history of anomalies. The fetus was followed through the remainder of the pregnancy with a repeat ultrasound at 32-33 weeks EGA with no new findings. The fetus was suspected to have bladder exstrophy.

Delivery of the infant was uneventful with Apgars of 8 and 9. On physical examination, a large defect in the infraumbilical abdominal wall was noted with exstrophy of the bladder and vagina, and an omphalocele (fig. 4).

Fig. 4: The exstrophy (yellow arrows) after creation of an ostomy (upper right). Note the hemiclitoris (blue arrows). 

The newborn underwent immediate operation for an ostomy. At surgery, the right aspect of the abdominal wall defect contained exstrophied bladder with two urethral orifices. The left side of the defect contained an enlarged vagina with a rectovaginal fistula. There were two cervices and a bicornuate uterus. The pubic rami were widely separated with a hemiclitoris on each side.

Examination of the gastrointestinal tract revealed normal position of the small bowel and colon. The rectum entered into the vagina, and an anal dimple was present. A single normal-appearing appendix was noted.

The patient underwent a colostomy and repair of the omphalocele. Due to the severity of the separation of the pubic rami, closure of the exstrophy was postponed until anterior ileostomies could be performed at approximately six months.

Case #2

A 28-year-old G₁P₀ was referred at 17 weeks" gestation for sonographic evaluation of her twin pregnancy. She had conceived in her first in vitro fertilization attempt and an early ultrasound examination had revealed two fetuses in separate gestational sacs. At the time of our examination, bi-amniotic, bi-chorionic twin gestation was suspected with biometry consistent with 17 weeks and normal amniotic fluid in both sacs.

Further examination revealed a partially solid mass protruding from the lower abdominal wall of one fetus (fig. 5-6).

Fig. 5: Longitudinal scan of the lower abdomen. The cord insertion is visualized above the protruding mass that contains bladder and bowel loops.

Fig. 6: The bladder clearly identified between both umbilical arteries, before their entrance into the cord.

The mass contained small cystic areas as well as a larger cystic region thought to be the fetal bladder at time of examination. The mass protruded from the lower abdomen, and a longitudinal scan showed the low but intact cord insertion. The fetal kidneys appeared normal with normal amount of amniotic fluid; since no intact bladder was visualized, an exstrophy was suspected. The rest of the examination of this fetus was unremarkable, and so was that of the second fetus.

The patient had repeat sono­grams every 2 weeks. Although the mass did not grow, it was evident at subsequent examinations that it included bowel loops. There was no deterioration of the upper urinary tract system. At 23 weeks gestation, a dilated cervix was found and the patient was placed on bed rest. At 27 weeks gestation, the membranes ruptured spontaneously and a cesarean section was performed.

Postnatal course

The first baby to be delivered was a boy with a weight of 950g. He did well and eventually went home. The second infant was a girl and she weighed 1010g. This infant had cloacal exstrophy with bowel, urinary and genital organs protruding from the anterior abdominal wall (fig. 7).

Fig. 7w: The 27-week fetus after delivery. Note the protruding mass from the anterior abdominal wall.

The infant had an imperforated anus but normal-appearing bowel. The uterus and vagina were split in the middle, and a very small bladder was noticed. A small occult spina bifida was detected, but no other skeletal anomalies were noticed.

The baby underwent initial surgery the day after delivery. The imperforated anus was corrected and, because of normal-appearing anus and rectum, no ostomy was performed. The bowel and internal genital organs were replaced into the abdominal cavity and the abdominal wall was closed. The spina bifida was corrected but needed two repeat surgeries due to infections. There were no further operations on the abdomen, and at the age of 18 months the infant is suffering from fecal and urinary incontinence. The fecal incontinence is due to lack of proper control of sphincters and is treated with hardening of the stools. The bladder incontinence is due to a very small bladder and will be corrected in the future. The infant is well developed and undergoes physiotherapy to enhance normal walking.

Discussion

Prevalence

Cloacal exstrophy is a rare congenital anomaly occurring in 0.25-0.5:10,000 births^1,2. It is the most severe form of the group of anomalies termed the exstrophy–epispadias complex. Of this group, which have in common a mal-development of mesoderm near the cloaca, bladder exstrophy in the most common form occurring in 0.3:10,000¹ births followed by epispadias 0.08-0.25:10,000.

Embryology

Review of the embryology of the urinary bladder, genitalia, and rectum is important in understanding the pathogenesis of cloacal exstrophy. The cloacal membrane forms the ventral portion of the cloacal pouch. Two concomitant mesodermal migrations take place near the 5^th or 6^th week of gestation. Just beneath the umbilicus a mesodermal proliferation extends inferiorly to form the infraumbilical abdominal wall and genital tubercle⁴. This migration repositions the cloacal membrane so that it becomes caudal in location.

A second mesodermal proliferation, the urorectal septum, divides the cloaca into the urogenital sinus anteriorly and the rectum posteriorly. The urorectal septum eventually fuses with the cloacal membrane, dividing it into the urogenital membrane anteriorly and the anal membrane posteriorly.

If the infraumbilical mesoderm fails to develop properly and the cloacal membrane remains ventral in location, bladder exstrophy results as the cloacal membrane resolves (fig. ) If this occurs before the urorectal septum has divided the urogenital sinus from the rectum, the resultant malformation is cloacal exstrophy. Marshall and Muecke propose that the cloacal membrane acts as a wedge preventing the fusion of the lateral mesoderm⁵.

 In classical cloacal exstrophy there is anomalous exposure of bowel separating two hemibladders. Hindgut and midgut malformations are common. Typically the descending colon ends in a blind pouch and the anus and rectum do not develop. The midgut abnormalities include non-rotation, deficiency of distal ileum, and exposure of bowel (felt to be cecum) through the hemi­bladders.

Ultrasound appearance

Less than a dozen of prenatal sonographic diagnoses of cloacal exstrophy have been reported^8-15. It is important to realize that in the exstrophies, the protruding mass does not contain any large cystic areas as it does not contain the urine that is excreted directly from the ureters into the amniotic fluid. As was the case in both our patients, the amount of amniotic fluid and upper urinary tracts are normal as there is no obstruction to flow. If a normal bladder cannot be visualized and an anterior mass is found, it is important to examine the cord insertion as this will help in the differential diagnosis between the exstrophies and gastroschisis and omphalocele. Ambiguous genitalia are important findings and visualization of normal external genitalia will probably exclude the diagnosis of bladder or cloacal exstrophy. Color Doppler imaging to correctly identify both umbilical arteries is an important diagnostic tool for localization of the bladder in the lower fetal abdomen (fig. 7).

Etiology

The etiology of cloacal exstrophy is unknown. The incidence is sporadic.

Associated anomalies

Cloacal exstrophy is commonly associated with other anomalies, much more so than bladder exstrophy (Table 1).

Approximately 70-90% of patients with cloacal exstrophy have an omphalocele. The association of an omphalocele, exstrophy of the cloaca, imperforated anus and spinal abnormalities (meningocele) is referred to as the OEIS complex. Other commonly associated anomalies include cardiovascular, central nervous system, single umbilical artery, vertebral anomalies (46%), upper urinary tract (42%) malrotation (30%), double appendix (30%), absent appendix (21%), short small bowel (19%), small bowel atresia (5%), abdominal musculature deficiency (1%)³. Upper urinary tract anomalies include pelvic kidney, horseshoe kidney, hypoplastic kidney and solitary kidney². Vertebral mal­for­mations include sacralization of L5, congenital scoliosis, sacral agenesis, and interpedicular widening⁶.

Resulting anomalies

In addition to anomalous exposure of bowel through the abdominal wall separating two hemibladders, resulting anomalies include anorectal agenesis, separation of pubis, bifid penis and undescended testes in males; bifid clitoris, duplex vagina, bicornuate uterus in females. Duplex or absent appendix may be seen.

Differential diagnosis

The differential diagnosis for cloacal exstrophy includes bladder exstrophy, omphalocele, gastroschisis and occasionally, sacrococcygeal teratoma. Non-visualization of the bladder should help differentiate the exstrophy–epispadias complex from isolated omphalocele or gastroschisis.

Prognosis

The prognosis depends on the presence of associated anomalies. Prior to 1960 cloacal exstrophy was considered to be uniformly fatal. Since then, the mortality has decreased to less than 50%². A recent reports indicates that 3-4 hours of urinary continence has been achieved in nearly half of one group of patients with repaired cloacal exstrophy. Reproduction in a patient with cloacal exstrophy has not been reported.

Management

Because of the elevated maternal serum alpha-fetoprotein, a large number of these fetuses will be detected by alpha-FP screening. Karyotyping, to exclude aneuploidies, can be offered, although aneuploidies are not typically associated with cloacal exstrophy.

Early sonographic detection and correct diagnosis of the anomaly is important for differential diagnosis and planning of prompt surgical intervention to prevent damage to the exposed organs. When the condition is detected before viability, the condition and its prognosis should be discussed with a team of perinatologist, pediatric surgeons, and genetic counselors. The option of termination can be offered.

Postnatal management

Usually, a staged surgical approach is used in management of patients with cloacal exstrophy⁷. Repair of the omphalocele and construction of an ileostomy or colostomy is performed immediately after birth. If ileum and colon are separate, anastomosis of these bowel segments is performed. Sexual assignment is dependent on the adequacy of the phallus, and this decision is typically made early.

In most cases, after a period of observation and nutritional support primary bladder repair or urinary diversion is performed at approximately nine to twelve months. If primary bladder repair is not feasible, urinary diversion to a ileal or colon conduit can be used. There is, however, some encouraging recent experience with early primary closure/reconstruction in the first few days of life.

Reconstruction of genitalia is, otherwise, usually carried out between the ages of 1 to 5 years. In females, duplicated vagina may require excision of the septum. In males the phallus is lengthened using the proximal portion of the corpora. However, most genetic males with cloacal exstrophy do best if the undergo orchiectomy very early in life and are reconstructed as females.

References

1. Tank ES, Linderaner SM: Principles of management of exstrophy of the cloaca. Am J Surg 119.95,1970.

2. Jeffs RD: Exstrophy, epispadias, and cloacal and urogenital sinus abnormalities. Ped Clin North Am 34:1233-57,1987.

3. Spencer R: Exstrophia splanchnica.Surgery 57:751,1965.

4 Davies J: Developoment of the urogenital system, ln Davies, J: Human Development Anatomy, New York, The Ronald Press Company 1963.

5. Marshall VF and Muecke EC: Variationbs in exstrophy of the bladder. J Urol 88:766,1962.

6. Loder RT, Dayiogler MM: Association of congenital vertebral malformations with bladder and cloacal exstrophy. J Pediatr Ortho 12:38993,1990.

7. Flanigan RC, Casale AJ, McRoberts JW: Cloacal exstrophy. Urology 23:22733,1984.

8. Meglin AJ; Balotin RJ; Jelinek JS et al.: Cloacal exstrophy: radiologic findings in 13 patients. AJR 1990, 155:1267-72

9. Nishi T, Yamoto M, Nakano R Prenatal diagnosis of exstrophy of the cloaca with ectopia cordis. Asia Oceania J Obstet Gynaecol. 1988, 14:213-7

10. Kutzner DK, Wilson WG, Hogge WA: OEIS complex (cloacal exstrophy): prenatal diagnosis in the second trimester. Prenat-Diagn. 1988, 8:247-53

11. Shalev E, Feldman E, Weiner E et al.: Prenatal sonographic appearance of persistent cloaca. Acta Obstet Gynecol Scand. 1986, 65: 517-8

12. Lande-IM; Hamilton-EF: The antenatal sonographic visualization of cloacal dysgenesis. J Ultrasound Med. 1986, 5: 275-8

13. Meizner I, Bar Ziv J: Prenatal ultrasonic diagnosis of cloacal exstrophy. Am J Obstet Gynecol. 1985, 153: 802-3

14. Meizner I, Bar Ziv J: In utero prenatal ultrasonic diagnosis of a rare case of cloacal exstrophy. JCU. 1985, 13: 500-2

15. Haygood VP, Wahbeh CJ: Prospects for the prenatal diagnosis and obstetric management of cloacal exstrophy. A report of two cases. J Reprod Med. 1983, 28: 807-10